Peter M. Groen / openbr

* Make OpenBR compatible with OpenCV 4.X (tested with 4.5.1). There is a loss in functionality with this port. See TODO.md for outstanding issues

* Add ForestInductionTransform back into forest.cpp

* Add boost back in to OpenBR. This was difficult because OpenCV 4 dropped the C persistence layer, which all of the boost classes use. The new 3rdparty/opencv2-compat directory adds the C persistence layer back in, along with the old OpenCV ML classes that were removed for 4.X

* Add boosted forest plugin back in

* Freeing memory only leads to terrible consequences! Both of these cases caused double frees when the pointers were freed. This solution definitely has a memory leak during training, but it does work

* Add InputOutputArray operator

* Properly print matrices with newlines

* Bug fixes

* opencv still defines these

* updated module dependencies

* bump eigen to fix compile error

* opencv ios lib location has changed

* sift now part of features2d

Co-authored-by: Jordan Cheney <jordan@rankone.io>
Co-authored-by: Scott Klum <scott@rankone.io>
Co-authored-by: Josh Klontz <josh@rankone.io>

The Build Instructions link pointed to the old doxygen docs instead of the new docs.

Bitdeli is broken

* upstream/master: (108 commits)
  Add vbb annotations to seq files
  Add all the bbs in a single Template
  Remove "bad idea," fix appending empty bbs
  more robust search for openbr
  Use our fork of cvmatio for a better install and move non-find logic to top CMakeLists
  install cvmatio libs (well, only for mac...)
  Add vbbGallery (if cvmatio is being used)
  Add cvmatio library as optional 3rd party lib
  Heatmap improvements
  Ignore the Caltech annotations
  Add SeqReader to Stream to process Caltech Pedestrian seq files
  Add Caltech Pedestrians dataset to downloadDatasets.sh
  Bug fix with linspace
  linspace bug fix
  Linspace helper function
  Better cropping for eyes
  strip subdirectory from OPENBR_DIR to ensure it points to the root dir
  fixed #107
  fixed set-but-unused warning
  reintroduced useGui flag so it can be overridden
  ...

Conflicts:
	README.md
	openbr/gui/utility.cpp
	openbr/plugins/stream.cpp